- 著者
-
Mizuno Tsunefumi
Miyawaki Ryohei
Ebisawa Ken
KUBOTA Aya
MIYAMOTO Masao
WINTER Lisa
UEDA Yoshihiro
ISOBE Naoki
MAKISHIMA Kazuo
- 出版者
- Published for the Yukawa Institute for Theoretical Physics and the Physical Society of Japan
- 雑誌
- Progress of theoretical physics. Supplement (ISSN:03759687)
- 巻号頁・発行日
- no.169, pp.229-233, 2007-12-19
- 参考文献数
- 24
- 被引用文献数
-
1
We report about the Suzaku observation of two ultraluminous X-ray sources (ULXs), X-1 and X-2, in NGC1313, together with their spectra by XMM-Newton. During the observation, both showed intensity-correlated spectral changes. The brighter source, X-1, exhibited the highest luminosity (~3×10^<40>erg s^<-1>) ever recorded from this source. Its spectral variation is ascribed to a strong power-law like component with a mild high energy curvature, while about 10% of the flux is carried by a stable soft component modeled by a cool disk emission. These properties suggest that the source was in the "very high" state, wherein the disk emission is strongly Comptonized and the optically-thick disk is truncated at a large radii or cooled off. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor disk model with the innermost disk temperature of 1.2-1.3keV, and becomes flatter as the source gets brighter. Hence X-2 is interpreted to be in a slim disk state. These results suggest that the two ULXs host black holes of a few tens to a few hundreds solar masses.